Normal tissue sensitivity

Question 1

dose constraint for the brain?

Answer 1

max dose: 50Gy

Question 2

What is the toxicity end point for the brain?

Answer 2

Symptomatic necrosis
Reduced cognitive development in children receiving whole- brain RT

Brain very sensitive to more than 2Gy per fraction and twice daily treatment

Question 3

Is the brain a serial or parallel structure?

Answer 3

Parallel

Question 4

What is the alpha beta ratio of the brain?

Answer 4

2.9

Question 5

What is the dose constraint for the optic chiasm?

Answer 5

Max dose: 55Gy

Question 6

Toxicity end point for the optic chiasm?

Answer 6

Potential for partial visual loss on section of optic nerve receiving dose

Optic neuropathy

Question 7

Is the optic chiasm serial or parallel?

Answer 7

serial

Question 8

What is the dose constraint for the brain stem?

Answer 8

Whole brainstem can receive no more than 54GY

Question 9

Is the brain stem serial or parallel?

Answer 9

Serial

Question 10

What is the toxicity end point for the brain stem?

Answer 10

Permanent cranial neuropathy or necrosis

Question 11

What is the alpha beta ratio for the brain stem?

Answer 11

2.5-3.3

Question 12

Max dose for the spinal cord?

Answer 12

Max dose: 45Gy it actually says 50 Gy in QUANTEC

Question 13

What is the toxicity end point for the spinal cord?

Answer 13

Myelopathy

0.2% myelopathy with 50Gy (2Gy/#)

6% mylelopathy with 60Gy (2Gy/#)

Question 14

Is the spinal cord serial or parallel?

Answer 14

serial

Question 15

Alpha beta ratio for the spinal cord?

Answer 15

0.87

Question 16

Max dose to the salivary glands?

Answer 16

Single parotid limit of 20Gy

Both parotids linnet of 25Gy
Submandibulars limit to 35Gy to help

DVH’s not reliable as GLANDS SHRINK DURING TREATMENT and gland sparing decreases

Question 17

Toxicity end point for the salivary glands?

Answer 17

Long term parotid salivary function reduced.

Question 18

are the salivary glands serial or parallel?

Answer 18

Parallel

Question 19

Larynx and Pharynx dose constraint?

Answer 19

Absolute limit of 66Gy

40-45Gy if larynx is not the target structure

Question 20

Toxicity end point for the larynx and pharynx?

Answer 20

Pharynx: Dysphagia
Larynx: Vocal dysfunction, Oedema, Aspiration

Question 21

Dose constraint for the lung?

Answer 21

V20 limit 30-35%

Question 22

What is the toxicity end point for the lung?

Answer 22

Fibrosis (a/b 3.5)

Pneumonitis (a/b 4)

Question 23

Is the lung serial or parallel?

Answer 23

Parallel

Question 24

What is the alpha beta ratio for the lung?

Answer 24

3.5-4

Question 25

What is the dose constraint for the heart?

Answer 25

V25Gy

Question 26

What are the toxicity end points of the heart?

Answer 26

Long term Cardiac mortality Diffuse myocardial fibrosis Pericarditis

Question 27

Is the heart serial or parallel?

Answer 27

Mixed serial/parallel

Question 28

What is the max dose for the oesophagus?

Answer 28

40-50Gy to limit acute oesophagitis

Question 29

Toxicity end point for the oesophagus?

Answer 29

Oesophagitis – grade 3 acute

Question 30

Is the oesophagus serial or parallel?

Answer 30

Parallel

Question 31

What is the dose constraint for the liver?

Answer 31

Whole liver (mets) 30Gy Primary liver: 28Gy

Question 32

Toxicity end point for the liver?

Answer 32

Radiation induced liver disease

Question 33

Is the liver serial or parallel?

Answer 33

Highly parallel

Question 34

Dose constraint for the small bowel and stomach?

Answer 34

Hard to delineate with contrast 50Gy limit 15Gy <120 cc (cubic centimeters) – which is 120 mL

Question 35

Toxicity end point for the stomach and small bowel?

Answer 35

Ulceration | Grade 3+ toxicity

Question 36

Are the stomach and small bowel serial or parallel?

Answer 36

Serial

Question 37

Bladder dose constraints?

Answer 37

V80 <15% V75< 25% V65 <50%

Question 38

Is the bladder serial or parallel?

Answer 38

Mixed-parallel

Question 39

What is the toxicity end point for the bladder?

Answer 39

Grade 3+ toxicity

Question 40

What are the dose constraints for the rectum?

Answer 40

V50Gy < 50% V70Gy < 20% V75Gy < 15%

Question 41

Toxicity end point for the rectum?

Answer 41

Grade 3+ late rectal toxicity

Question 42

Is the rectum serial or parallel?

Answer 42

Serial/Parallel

Question 43

What are the dose constraints for the penile bulb?

Answer 43

D90 | D60-70

Question 44

What is the toxicity end point for the penile bulb?

Answer 44

Severe erectile dysfunction

Question 45

Is the penile bulb serial or parallel?

Answer 45

Parallel